Energy harvesters for use in operating low power electronics have been an active area of interest for decades. Vibrational energy harvesters may be configured to collect the energy associated with mechanical movement by converting mechanical energy to some other form of energy, such as electrical energy, for immediate use and/or storage for later use. For example, piezoelectric materials can generate an electrical potential when mechanically deformed and can be connected to an electrical load or storage device to harvest energy from mechanical vibrations. Such energy harvesters could be used to operate wireless sensors in remote locations or in other applications where battery replacement is impractical. Energy harvesters could also serve to reduce reliance on batteries, which often include hazardous materials, and reduce the need for electrical wiring in some cases. However, such energy harvesters have not been adopted for widespread use, due in part to certain size, frequency and amplitude constraints that render them unsuitable for many practical applications.
One application for energy harvesters is implantable biomedical devices. Many vibrational energy harvesters that are configured to extract energy from human motion are designed for attachment to the limbs. Where the biomedical device is intended for implant in the torso, it is sometimes preferable to include the energy harvester as part of the device package. One type of energy harvester that can be used in the torso is a microbial fuel cell, which generally relies on the oxidation of glucose to generate power. Another type of energy harvester uses a piezoelectric film wrapped around an artery and is configured to harvest energy from artery expansions. Another type of energy harvester includes piezoelectric ribbons printed onto a rubber substrate and is configured to harvest energy from lung expansion during respiration.